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Thursday, November 2, 2017

21 INCH LG Ultra slim TV VERTICAL CLOSED

A friend of mine called me to pass by his place to check on
his television which was indicating no signal on the screen.

After passing by I went straight to the antenna connector at
the decoder and noticed that it was loose which I re-connected and the problem
was solved.

After the signal was restored I noted the picture was not
covering the full screen at the top and at the bottom and I pointed it to the
owner seems like the TV also has another problem but according to the owner he
was okay with the set.

I went my way and after two to three months I received an
urgent call from the same guy and this time he told me the TV is now dead with
a single horizontal line across the screen and this brought to my remembrance
that the TV has already started showing vertical failure symptoms when attended
it last.

I passed by his place and took with me the inner board to my
workshop since there was no point of carrying the whole tube.

I started scanning around the vertical circuit and I picked
one capacitor C457(2200uF/35V) which has top slightly swollen.

I decided to google this model from the internet so that I
can get to know why this capacitor has such an impact on the vertical circuit
and this is what I found.

Looking at the capacitor C457 (2200uf/35V) you will note
that its main function is to block DC and Allow AC in this case the vertical pulses to pass
through to the vertical yoke.

So once this capacitor dried up blocked the vertical pulses
from going into the vertical yoke and hence the symptoms.

Please remember all voltages to the vertical I.C were found
good and therefore next time you get such a problem it is important to check
this capacitor before replacing the vertical I.C.

thanks again for your informative articles sir. I have a problem with the crt tv that I'm repairing on hand.It has 142 volts at HOT collector but has no volt at the base what else is next to be done sir humphrey. Your reply will give me confidence to resume with my concern sir.thanking you in advance.Romeo